1. Field of the Invention
The present invention relates to a door lock and, more particularly, to a door lock which can be assembled smoothly and correctly.
2. Description of Related Art
As shown in FIG. 1, there is a door lock that includes a tubular casing 90 having a front end-plat 901 covered with a panel 900, for the purpose of receiving a bolt 91, a linking piece 92, a trigger 93 and a tumbler 94 therein.
The bolt 91 is connected to the linking piece 92, which is in turn connected to a slider 97 by a clip ring 96. The slider 97 has two pairs of opposite cogs 971, 972, with each pair being adapted to mesh with paws 981 of an annular follower 98 rotatably positioned in aligned holes 991 of a rear cover 99. The rear cover 99 can be moved, relative to opposite guides 90a, 90b, to such positions that the paws 981 of the follower 98 may mesh with the cogs 971 or cogs 972. When the follower 98 is turned, the paws 981 push the cogs 971, 972, so as to move the slider 97 and hence the bolt 91 backward. The bolt 91 will return by the action of compressed springs 95 immediately after the follower 98 is released.
In the conventional door lock, it is the panel 900 that defines a furthest or extended position for the bolt 91. When the lock is being assembled, the panel 900 must be held on the front end-plate 901, such as with rubber bands, to confine the spring-loaded bolt 91 and trigger 93 in the casing 90 before the panel 900 is riveted to the plate 901. If the front panel 900 is separated undesirably from the front end-plate 901, the bolt 91 and then the trigger 93 will move further forward.
The tumbler 94 is then turned by the action of the spring 95 and its hooked front end 941 will not be pressed against a protrusion 931 of the trigger 93 but be moved to the back of the protrusion 931 instead, thus blocking the way the trigger 93 and the bolt 91 may be moved back. The door lock is useless unless it is dismantled and the assembling process is repeated.
In addition, it is usual to find that the annular follower 98 is placed so incorrectly that one of its paws 981 projects outward from the cogs 971, 972 of the slider 97, as shown in FIG. 2. The non-rotatable follower 98 results in a useless lock.
The object of the present invention is to provide a door lock which can be assembled smoothly.
Another object of the present invention is to provide a door lock which can be assembled correctly.
An improved door lock includes a tubular casing that has a front end-plate covered with a front panel in order to receive and confine a bolt, a linking piece, a spring-loaded trigger and a tumbler in the casing. The bolt is movable in the tubular casing between an extended position and a retracted position, and is spring-loaded in such a way that it tends to be moved to the extended position. The spring-loaded trigger has a front end normally extended out of the casing, and the tumbler is adapted to retain the bolt in the extended position when the front end of the trigger is depressed while the bolt is moved to the extended position.
Two opposite guides are situated behind the tubular casing and joined together. The guides are formed with respective grooves aligned with each other, with a slider movable between the guides forward and backward. The slider is connected to the bolt through the linking piece and is formed with a first pair of opposite cogs and a second pair of opposite cogs. An annular follower is positioned in place in the groves of the guides and has a pair of paws for selectively pushing the pairs of opposite cogs, thereby moving the slider and hence the bolt backward as the follower is turned.
In the present invention, the slider has a pair of indentations defined therein while one of the guides have a pair of teeth engagable with rear ends of the indentations when the bolt is fully extended. This provides the bolt with an extended position independent from the front panel.
Furthermore, one of the guides is additionally formed with a first pair of opposite stops and a second pair of opposite stops, with the first pair of opposite stops located between the first and second pairs of cogs and the second pair of opposite stops located behind the second pair of cogs when the bolt is in its extended position.
In a preferred embodiment, the slider further has a pair of notches formed at a front end thereof and a clip ring is held both around a heck of the linking piece and in the notches of the slider, so as to connect the slider to the linking piece.
In a highly preferred embodiment, there is a rear cover having a pair of aligned through-holes in which annular follower is rotatably positioned. The rear cover is situated behind the tubular casing in either one of two positions, including a first position in which the paws of the annular follower may push the fist pair of opposite cogs, and a second position in which the paws of the annular follower may push the second pair of opposite cogs.